package com.xb.loan.util;


import org.apache.commons.beanutils.ConvertUtils;
import org.apache.commons.beanutils.PropertyUtils;
import org.apache.commons.beanutils.converters.DateConverter;
import org.apache.commons.lang3.StringUtils;

import java.lang.reflect.*;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Date;
import java.util.List;

/**
 * 
 * 反射的 Utils 函数集合
 * 提供访问私有变量, 获取泛型类型 Class, 提取集合中元素属性等 Utils 函数
 *
 */
public class ReflectionUtils {
    
    /**
     * 将反射时的 "检查异常" 转换为 "运行时异常"
     * @return
     */
    public static IllegalArgumentException convertToUncheckedException(Exception ex){
        if(ex instanceof IllegalAccessException || ex instanceof IllegalArgumentException
                || ex instanceof NoSuchMethodException){
            throw new IllegalArgumentException("反射异常", ex);
        }else{
            throw new IllegalArgumentException(ex);
        }
    }
    
    /**
     * 转换字符串类型到 toType 类型, 或 toType 转为字符串
     * @param value:  待转换的字符串
     * @param toType: 提供类型信息的 Class, 可以是基本数据类型的包装类或指定格式日期型
     * @return
     */
    public static Object convertValue(Object value, Class<?> toType){
        try {
            DateConverter dc = new DateConverter();
            
            dc.setUseLocaleFormat(true);
            dc.setPatterns(new String[]{"yyyy-MM-dd", "yyyy-MM-dd HH:mm:ss"});

            ConvertUtils.register(dc, Date.class);
            
            return ConvertUtils.convert(value, toType);
        } catch (Exception e) {
            e.printStackTrace();
            throw convertToUncheckedException(e);
        }
    }

    /**
     * 提取集合中的对象的属性(通过 getter 方法), 组成 List
     * @param collection: 来源集合
     * @param propertyName: 要提取的属性名
     * @return
     */
    @SuppressWarnings("unchecked")
    public static List fetchElementPropertyToList(Collection collection, String propertyName){
        List list = new ArrayList();
        
        try {
            for(Object obj: collection){
                list.add(PropertyUtils.getProperty(obj, propertyName));
            }
        } catch (Exception e) {
            e.printStackTrace();
            convertToUncheckedException(e);
        }
        
        return list;
    }
    
    /**
     * 提取集合中的对象属性(通过 getter 函数), 组合成由分隔符分隔的字符串
     * @param collection: 来源集合
     * @param propertyName: 要提取的属性名
     * @param seperator: 分隔符
     * @return
     */
    @SuppressWarnings("unchecked")
    public static String fetchElementPropertyToString(Collection collection, String propertyName, 
            String seperator){
        List list = fetchElementPropertyToList(collection, propertyName);
        return StringUtils.join(list, seperator);
    }
    
    /**
     * 通过反射, 获得定义 Class 时声明的父类的泛型参数的类型
     * 如: public EmployeeDao extends BaseDao<Employee, String>
     * @param clazz
     * @param index
     * @return
     */
    @SuppressWarnings("unchecked")
    public static Class getSuperClassGenricType(Class clazz, int index){
        Type genType = clazz.getGenericSuperclass();
        
        if(!(genType instanceof ParameterizedType)){
            return Object.class;
        }
        
        Type [] params = ((ParameterizedType)genType).getActualTypeArguments();
        
        if(index >= params.length || index < 0){
            return Object.class;
        }
        
        if(!(params[index] instanceof Class)){
            return Object.class;
        }
        
        return (Class) params[index];
    }
    
    /**
     * 通过反射, 获得 Class 定义中声明的父类的泛型参数类型
     * 如: public EmployeeDao extends BaseDao<Employee, String>
     * @param <T>
     * @param clazz
     * @return
     */
    @SuppressWarnings("unchecked")
    public static<T> Class<T> getSuperGenericType(Class clazz){
        return getSuperClassGenricType(clazz, 0);
    }
    
    /**
     * 循环向上转型, 获取对象的 DeclaredMethod
     * @param object
     * @param methodName
     * @param parameterTypes
     * @return
     */
    public static Method getDeclaredMethod(Object object, String methodName, Class<?>[] parameterTypes){
        
        for(Class<?> superClass = object.getClass(); superClass != Object.class; superClass = superClass.getSuperclass()){
            try {
                //superClass.getMethod(methodName, parameterTypes);
                return superClass.getDeclaredMethod(methodName, parameterTypes);
            } catch (NoSuchMethodException e) {
                //Method 不在当前类定义, 继续向上转型
            }
            //..
        }
        
        return null;
    }
    
    /**
     * 使 filed 变为可访问
     * @param field
     */
    public static void makeAccessible(Field field){
        if(!Modifier.isPublic(field.getModifiers())){
            field.setAccessible(true);
        }
    }
    
    /**
     * 循环向上转型, 获取对象的 DeclaredField
     * @param object
     * @param filedName
     * @return
     */
    public static Field getDeclaredField(Object object, String filedName){
        
        for(Class<?> superClass = object.getClass(); superClass != Object.class; superClass = superClass.getSuperclass()){
            try {
                return superClass.getDeclaredField(filedName);
            } catch (NoSuchFieldException e) {
                //Field 不在当前类定义, 继续向上转型
            }
        }
        return null;
    }
    
    /**
     * 直接调用对象方法, 而忽略修饰符(private, protected)
     * @param object
     * @param methodName
     * @param parameterTypes
     * @param parameters
     * @return
     * @throws InvocationTargetException 
     * @throws IllegalArgumentException 
     */
    public static Object invokeMethod(Object object, String methodName, Class<?> [] parameterTypes,
            Object [] parameters) throws InvocationTargetException{
        
        Method method = getDeclaredMethod(object, methodName, parameterTypes);
        
        if(method == null){
            throw new IllegalArgumentException("Could not find method [" + methodName + "] on target [" + object + "]");
        }
        
        method.setAccessible(true);
        
        try {
            return method.invoke(object, parameters);
        } catch(IllegalAccessException e) {

        } 
        
        return null;
    }
    
    /**
     * 直接设置对象属性值, 忽略 private/protected 修饰符, 也不经过 setter
     * @param object
     * @param fieldName
     * @param value
     */
    public static void setFieldValue(Object object, String fieldName, Object value){
        Field field = getDeclaredField(object, fieldName);
        
        if (field == null)
            throw new IllegalArgumentException("Could not find field [" + fieldName + "] on target [" + object + "]");
        
        makeAccessible(field);
        
        try {
            field.set(object, value);
        } catch (IllegalAccessException e) {

        }
    }
    
    /**
     * 直接读取对象的属性值, 忽略 private/protected 修饰符, 也不经过 getter
     * @param object
     * @param fieldName
     * @return
     */
    public static Object getFieldValue(Object object, String fieldName){
        Field field = getDeclaredField(object, fieldName);
        
        if (field == null)
            throw new IllegalArgumentException("Could not find field [" + fieldName + "] on target [" + object + "]");
        
        makeAccessible(field);
        
        Object result = null;
        
        try {
            result = field.get(object);
        } catch (IllegalAccessException e) {

        }
        
        return result;
    }
}

